Background The most frequent myositis specific antibody (MSA) in the serum of patients with idiopathic inflammatory myopathies is anti-Jo-1. The presence of anti-Jo-1 define a distinct clinical phenotype, antisynthetase syndrome (ASS), which is characterized by poor prognosis and multiple organ involvement, such as myositis, interstitial lung disease (ILD), non-erosive arthritis, Raynaud's phenomen, mechanic's hand, skin rashes, and fever.
Objectives The aim of this study was to determine the clinical, serological, laboratory and genetic features of anti-Jo1 positive patients followed by our department.
Methods Retrospective analysis of medical records of 49 patients (42 female, 7 male) were reviewed. Anti-Jo-1 titer was detected with enzyme-linked immunosorbent assay. HLA DRB1, DQA1 and DQB1 genotype was determined using commercial sequence-specific oligonucleotide kit. Statistical analysis was performed using Pearson Chi2, Fisher exact test, or Spearman correlation.
Results The median age at diagnosis was 43±13,28 years (range: 18-70), 48 patients exhibited myositis (98%), 35 ILD (73%), 43 arthritis (88%), 32 Raynaud's phenomen (65%), 21 fever (43%), 16 mechanic's hand (33%), 27 skin rash (55%) and 6 dysphagia (12%). We could detect significant correlation between the initial anti-Jo-1 titer and the first CK (R=0,328; p=0,003) and CRP (R=0,374; p=0,016) level. Furthermore anti-Jo1 levels during disease course had significant correlation to the corresponding CK (R=0,497; p<0.001), and CRP (R=0,325; p<0.001) level. The most frequent antibody besides anti-Jo-1 was anti-SSA (28/49; 57%). The anti-Jo-1+/SSA+ population had younger age at the diagnosis (36,12±11,08 vs. 47,22±12,87; p=0,004), lower rate of ILD (53% vs. 81%; p=0,039), but higher maintaining steroid (methylprednisolone) dose (9,53 mg vs. 3,7 mg; p=0,031) compared to the Jo-1+/SSA- group. Higher (≥8 mg) maintaining steroid therapy was associated with higher initiating CRP (36,34 vs. 17,84 mg/l; p=0,014) ESR (33,87 vs. 19,81 mm/h; p=0,032) level and higher presence of fever (67% vs. 37%; p=0,038) at diagnosis but not with initiating CK (p=0,374), LDH (p=0,224) level or ILD presence (p=1). 68,96% of the patients were HLA DRB1*03 positive, where the CK level at diagnosis was significantly lower compared to the HLA DRB1*03 negative patients (2816,30 vs. 5969,44 U/l; p=0.04). 58.62% of the patients were positive for HLA DQA1*0501-DQB1*0201 haplotype, but no significant correlation was found regarding to any clinical or laboratory features.
Conclusions Our results confirm previously reported data from other centers considering the clinical features of anti-Jo1 positive patients. HLA DRB1*03 positivity was associated with lower CK level but has no influence on clinical or serological features. It seems that anti-Jo1 level might reflect disease activity; ESR, CRP levels, associated fever and anti-SSA positivity at the diagnosis could be considered as prognostic markers.
Disclosure of Interest None declared